Various techniques are known in the art for cardiac ablation therapy. U.S. Patent Publication No. 2010/0331658, whose disclosure is incorporated herein by reference, describes an open-irrigated catheter system comprising a tip section, a distal insert, and mapping electrodes. The tip section has an exterior wall that defines an open interior region within the tip section. The exterior wall includes mapping electrode openings and irrigation ports. The exterior wall is conductive for delivering radio frequency (RF) energy for an RF ablation procedure. The irrigation ports are in fluid communication with the open interior region to allow fluid to flow from the open interior region through the irrigation ports. The distal insert is positioned within the tip section to separate the open region into a distal fluid reservoir and a proximal fluid reservoir. The mapping electrodes are positioned in the mapping electrode openings in the tip section.
U.S. Patent Publication No. 2007/0006254, whose disclosure is incorporated herein by reference, describes a method of controlling a remote navigation system that orients the distal end of a medical device in response to user inputs, including interrupting the operation of the remote navigation system when the user inputs would navigate the medical device to a location where the impedance exceeds a predetermined value. A method of controlling ablation of cardiac tissue to block an errant signal causing an arrhythmia includes ablating tissue until there is a predetermined reduction in the amplitude of the errant signal or a predetermined reduction in local impedance.
U.S. Pat. No. 7,959,630, whose disclosure is incorporated herein by reference, describes assemblies, probes, and methods for creating circumferential lesions in tissue, e.g., the tissue within or around the ostium of a vessel. An ablation probe with an ablative structure can be placed in contact within or around the ostium of the vessel. A diagnostic probe can be introduced through a lumen within the ablation probe and inserted into the vessel. Energy can be provided to the ablative structure to create a circumferential lesion within or around the ostium of the vessel, and the diagnostic structure can be used to diagnose the tissue to determine whether the circumferential lesion can be properly created.
U.S. Patent Publication No. 2006/0253115, whose disclosure is incorporated herein by reference, describes catheters, systems, and methods which are provided for performing medical procedures, such as tissue ablation, adjacent the ostia of anatomical vessels, such as pulmonary veins. A catheter comprises an elongated flexible catheter body including a proximal shaft portion and a distal shaft portion, which has a proximal section pre-shaped to form a curve having an apex sized to be inserted into an anatomical vessel, such as a pulmonary vein, and a distal section configured to contact an ostium of the vessel when the curve apex is inserted within the vessel ostium. The catheter further comprises a steering mechanism configured for decreasing a radius of curvature of the curve.